Flow object children

• An atomic flow object has no children.
• A composite flow object normally has sequence of children (stream)
• A composite flow object can also have more than one stream
• Each stream is associated with a port of the flow object.
• No order between a flow object in one stream of a flow object and a flow object in another stream of that flow object.
• Ports that a flow object has depends on class and sometimes characteristics
• Example: fraction has numerator and denominator ports.